WO2015190000A1 - 窒化物半導体発光素子 - Google Patents
窒化物半導体発光素子 Download PDFInfo
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- WO2015190000A1 WO2015190000A1 PCT/JP2014/065792 JP2014065792W WO2015190000A1 WO 2015190000 A1 WO2015190000 A1 WO 2015190000A1 JP 2014065792 W JP2014065792 W JP 2014065792W WO 2015190000 A1 WO2015190000 A1 WO 2015190000A1
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- nitride semiconductor
- semiconductor layer
- light emitting
- light
- type nitride
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 91
- 150000004767 nitrides Chemical class 0.000 title claims abstract description 89
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 22
- 239000012535 impurity Substances 0.000 description 15
- 239000000758 substrate Substances 0.000 description 14
- 239000007789 gas Substances 0.000 description 12
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 12
- 229910021529 ammonia Inorganic materials 0.000 description 11
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 229910052594 sapphire Inorganic materials 0.000 description 7
- 239000010980 sapphire Substances 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 6
- 230000007547 defect Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000011777 magnesium Substances 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- 239000012159 carrier gas Substances 0.000 description 5
- 229910001873 dinitrogen Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910002704 AlGaN Inorganic materials 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- VCZQFJFZMMALHB-UHFFFAOYSA-N tetraethylsilane Chemical compound CC[Si](CC)(CC)CC VCZQFJFZMMALHB-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000004020 luminiscence type Methods 0.000 description 2
- 238000001004 secondary ion mass spectrometry Methods 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- IBEFSUTVZWZJEL-UHFFFAOYSA-N trimethylindium Chemical compound C[In](C)C IBEFSUTVZWZJEL-UHFFFAOYSA-N 0.000 description 2
- HECLRDQVFMWTQS-UHFFFAOYSA-N Dicyclopentadiene Chemical compound C1C2C3CC=CC3C1C=C2 HECLRDQVFMWTQS-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005424 photoluminescence Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/26—Materials of the light emitting region
- H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
- H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/0004—Devices characterised by their operation
- H01L33/0008—Devices characterised by their operation having p-n or hi-lo junctions
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/10—Details of semiconductor or other solid state devices to be connected
- H01L2924/11—Device type
- H01L2924/12—Passive devices, e.g. 2 terminal devices
- H01L2924/1204—Optical Diode
- H01L2924/12041—LED
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
- H01L2933/0008—Processes
- H01L2933/0033—Processes relating to semiconductor body packages
- H01L2933/0058—Processes relating to semiconductor body packages relating to optical field-shaping elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/025—Physical imperfections, e.g. particular concentration or distribution of impurities
Definitions
- the present invention relates to a nitride semiconductor light emitting device, and more particularly to a light emitting device with improved luminous efficiency.
- LEDs ultraviolet light emitting diodes
- the cause of this deep light emission is said to be light emission from defects and impurity levels in the light emitting layer, but it has not been clarified.
- Non-Patent Document 1 recognizes from the measurement of photoluminescence to the fact that C (carbon) has some influence on deep light emission.
- the present inventor can attenuate deep light emission by improving the quality of the light emitting layer if light emission at the defects or impurity levels in the light emitting layer is a cause of deep light emission. I guessed it. That is, it was speculated that deep light emission can be significantly attenuated by reducing defects and contained impurities (for example, C) in the light emitting layer as much as possible.
- impurities for example, C
- the same current is supplied to separate ultraviolet LED elements (51 to 55) having a main emission wavelength of 370 nm band, and for each of them, deep emission with respect to the emission output of the main emission wavelength and the light intensity of the main emission wavelength.
- the relationship of intensity ratio (hereinafter referred to as “deep intensity ratio”) was measured. The measurement results are shown in FIG.
- the LED elements 54 and 55 having a high light intensity at the main emission wavelength in the state where the same current is passed have a high-quality light-emitting layer with fewer defects and contained impurities than the LED elements 51 and 52. Conceivable.
- the deep intensity ratios of the LED elements 52 to 55 which are considered to have a light emitting layer having higher quality than that of the element are lowered. Considering only this point, it is considered that the deep intensity ratio can be lowered by improving the quality of the light emitting layer. In other words, it is possible to conclude that defects in the light emitting layer and light emission at the impurity level cause deep light emission.
- the quality of the light emitting layer is improved in this order since the light output of the main light emission wavelengths is significantly increased in the order of the LED elements 51, 52, 53, 54, 55, but the deep intensity ratio is decreased.
- the rate is significantly lower than the rate of improvement of the light emission output.
- the LED elements 54 and 55 are compared, the deep intensity ratio is hardly changed despite a sufficient difference in the light emission output.
- the present inventor considers that deep light emission is caused by another event different from light emission in defects or impurity levels in the light emitting layer, and investigates the cause. This led to the idea that the deep intensity ratio can be reduced.
- the nitride semiconductor light emitting device of the present invention is a nitride semiconductor light emitting device having a light emitting layer between an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, wherein the n-type nitride semiconductor layer comprises Al n It contains Ga 1-n N (0 ⁇ n ⁇ 1), and the contained C concentration is 1 ⁇ 10 17 / cm 3 or less.
- the inventors have intensively researched and found that deep light emission is strongly manifested from the light emitting element when the C concentration contained in the n-type nitride semiconductor layer increases. And it discovered that the light emission output of deep light emission could be significantly reduced with respect to the light emission output of the main light emission wavelength by making this C density
- a light-emitting element whose main emission wavelength is ultraviolet light is configured as a nitride semiconductor light-emitting element
- the effect of purple visible light corresponding to the bottom part of the peak wavelength is originally generated by emitting ultraviolet light.
- dark purple light should be emitted.
- the emission color becomes whitish because the purple light and the yellow light are mixed.
- the ultraviolet light emitting device when the ultraviolet light emitting device is similarly configured with the C concentration contained in the n-type nitride semiconductor layer being 1 ⁇ 10 17 / cm 3 or less as in the present invention, the emission color from the device becomes white. Poorness decreases. As the content C concentration is lowered, whitishness disappears and the emission color becomes deep purple. This also shows that deep light emission can be suppressed by reducing the C concentration contained in the n-type nitride semiconductor layer. Thus, the monochromaticity and light emission efficiency of the light emitting element can be improved.
- the problem of deep light emission appears remarkably in the case of an ultraviolet light emitting device having a main light emission wavelength of 375 nm or less. For this reason, in the ultraviolet light emitting element, the effect of suppressing deep light emission is maximized by setting the C concentration contained in the n-type nitride semiconductor layer to 1 ⁇ 10 17 / cm 3 or less. However, since some deep light emission occurs even if it is not an ultraviolet light emitting device, the C concentration contained in the n-type nitride semiconductor layer is similarly 1 ⁇ 10 5 even in a light emitting device having a main light emission wavelength exceeding 375 nm. The suppression effect of deep light emission is implement
- the main light emitting wavelength is an ultraviolet light emitting device having a wavelength of 375 nm or less
- the light emission intensity of yellow visible light wavelength is higher than the light emission intensity of this main light emitting wavelength.
- the ratio is 0.1% or less.
- the emission intensity of the yellow visible light wavelength is larger than the emission intensity of the main emission wavelength.
- the intensity ratio is 0.1% or less, and deep light emission is suppressed to a level that does not cause a problem.
- the nitride semiconductor light emitting device of the present invention since deep light emission is suppressed, a light emitting device having high monochromaticity and high light emission efficiency is realized.
- 1 is a schematic cross-sectional view of a nitride semiconductor light emitting device. It is a graph which shows the spectrum distribution of the light obtained when the same electric current is sent through three elements of Example 1, Example 2, and Comparative Example 1. 4 is a photograph showing a light emission mode when the same current is passed through the three elements of Example 1, Example 2, and Comparative Example 1. It is another schematic sectional drawing of the nitride semiconductor light-emitting device.
- the nitride semiconductor light emitting device of the present invention will be described with reference to the drawings.
- the dimensional ratio in the drawing does not necessarily match the actual dimensional ratio.
- FIG. 2 is a schematic cross-sectional view of the nitride semiconductor light emitting device 1.
- LED element 1 it is abbreviated as “LED element 1”.
- the LED element 1 is described as an ultraviolet light emitting element having a main emission wavelength of 370 nm, but the emission wavelength is not limited to this value.
- the LED element 1 is formed by laminating a support substrate 2, an undoped layer 3, an n-type nitride semiconductor layer 4, a light emitting layer 5, and a p-type nitride semiconductor layer 6 in this order from the bottom.
- the support substrate 2 is composed of a sapphire substrate. In addition to sapphire, Si, SiC, AlN, AlGaN, GaN, YAG, or the like may be used.
- the undoped layer 3 is formed of GaN. More specifically, it is formed of a low-temperature buffer layer made of GaN and an underlying layer made of GaN on the upper layer.
- the n-type nitride semiconductor layer 4 is composed of Al n Ga 1-n N (0 ⁇ n ⁇ 1) formed so that the concentration of C contained as an impurity is 1 ⁇ 10 17 / cm 3 or less. The A method for reducing the content C concentration will be described later.
- the light emitting layer 5 is formed of a semiconductor layer (AlGaInN light emitting layer) having a multiple quantum well structure in which, for example, a well layer made of GaInN and a barrier layer made of AlGaN are repeated. These layers may be undoped or p-type or n-type doped.
- the p-type nitride semiconductor layer 6 is composed of Al m Ga 1-m N (0 ⁇ m ⁇ 1). Note that, unlike the n-type nitride semiconductor layer 4, the p-type nitride semiconductor layer 6 may have a concentration of C contained as an impurity exceeding 1 ⁇ 10 17 / cm 3 . This point will also be described later.
- the LED element 1 may have a high-concentration p-type GaN layer for contact on the p-type nitride semiconductor layer 6.
- the n-type nitride semiconductor layer 4 exposed by etching may have an n-electrode on the upper layer and a p-electrode on the high-concentration p-type GaN layer.
- an undoped layer 3 is formed on the support substrate 2. This is realized, for example, by the following method.
- a sapphire substrate is prepared as the support substrate 2, and the c-plane sapphire substrate is cleaned. More specifically, for this cleaning, for example, a c-plane sapphire substrate is placed in a processing furnace of a MOCVD (Metal Organic Chemical Vapor Deposition) apparatus, and hydrogen gas with a flow rate of 10 slm is placed in the processing furnace. The temperature in the furnace is raised to, for example, 1150 ° C. while flowing.
- MOCVD Metal Organic Chemical Vapor Deposition
- a low-temperature buffer layer made of GaN is formed on the surface of the c-plane sapphire substrate, and an underlayer made of GaN is further formed thereon. These low-temperature buffer layer and underlayer correspond to the undoped layer 3.
- a more specific method for forming the undoped layer 3 is as follows. First, the furnace pressure of the ⁇ CVD apparatus is 100 kPa, and the furnace temperature is 480 ° C. Then, while flowing nitrogen gas and hydrogen gas with a flow rate of 5 slm respectively as carrier gases into the processing furnace, trimethylgallium (TMG) with a flow rate of 50 ⁇ mol / min and ammonia with a flow rate of 223000 ⁇ mol / min as the source gas For 68 seconds. Thereby, a low-temperature buffer layer made of GaN having a thickness of 20 nm is formed on the surface of the c-plane sapphire substrate.
- TMG trimethylgallium
- the furnace temperature of the MOCVD apparatus is raised to 1150 ° C. Then, while flowing nitrogen gas having a flow rate of 20 slm and hydrogen gas having a flow rate of 15 slm as a carrier gas in the processing furnace, TMG having a flow rate of 100 ⁇ mol / min and ammonia having a flow rate of 223000 ⁇ mol / min are introduced into the processing furnace as source gases. Feed for 30 minutes. As a result, a base layer made of GaN having a thickness of 3 ⁇ m is formed on the surface of the low-temperature buffer layer.
- n-type nitride semiconductor layer 4 (Formation of n-type nitride semiconductor layer 4) Next, an n-type nitride semiconductor layer 4 having a composition of Al n Ga 1-n N (0 ⁇ n ⁇ 1) is formed on the undoped layer 3.
- a more specific method for forming the n-type nitride semiconductor layer 4 is, for example, as follows. First, with the furnace temperature kept at 1150 ° C., the furnace pressure of the MOCVD apparatus is set to 30 kPa. Tetraethylsilane for doping TMG, trimethylaluminum (TMA), ammonia, and n-type impurities as source gases while flowing nitrogen gas having a flow rate of 20 slm and hydrogen gas having a flow rate of 15 slm as a carrier gas in the processing furnace. Is fed into the processing furnace for 30 minutes. Thereby, for example, an n-type nitride semiconductor layer 4 having a composition of Al 0.06 Ga 0.94 N and a thickness of 1.7 ⁇ m is formed in the upper layer of the undoped layer 3.
- the C concentration contained in the n-type nitride semiconductor layer 4 is 1 ⁇ 10 6. 17 / cm 3 or less.
- the V / III ratio can be about 2000.
- Tetraethylsilane also contains C atoms, but its flow rate is, for example, about 0.025 ⁇ mol / min, so the influence on the C concentration contained in the n-type nitride semiconductor layer 4 is negligible compared to TMG and TMA. it can.
- the content C concentration of the generated n-type nitride semiconductor layer 4 was 5 ⁇ 10 17 / cm 3 (Comparative Example 1 described later). Further, when the V / III ratio is 2000, the content C concentration is 1 ⁇ 10 17 / cm 3 (Example 2 described later), and when the V / III ratio is 4000, the content C concentration was 5 ⁇ 10 16 / cm 3 (Example 1 described later).
- the content C concentration of the generated n-type nitride semiconductor layer 4 was measured by SIMS (Secondary Ion Mass Spectrometry).
- CMG is contained in the constituent molecules of TMG and TMA, which are raw material gases.
- ammonia does not contain C atoms. For this reason, by increasing the V / III ratio, the concentration of C contained in the n-type nitride semiconductor layer 4 to be formed can be reduced.
- the growth pressure is preferably 30 kPa or more and 100 kPa or less, and more preferably 50 kPa or more and 100 kPa or less.
- silicon (Si), germanium (Ge), sulfur (S), selenium (Se), tin (Sn), tellurium (Te), or the like is used. be able to. Among these, silicon (Si) is particularly preferable.
- the light emitting layer 5 having a multiple quantum well structure made of AlGaInN is formed on the n-type nitride semiconductor layer 4.
- the furnace pressure of the MOCVD apparatus is set to 100 kPa, and the furnace temperature is set to 830 ° C. Then, while flowing nitrogen gas having a flow rate of 15 slm and hydrogen gas having a flow rate of 1 slm as a carrier gas in the processing furnace, TMG having a flow rate of 10 ⁇ mol / min, trimethylindium (TMI) having a flow rate of 12 ⁇ mol / min, and A step of supplying ammonia at a flow rate of 300,000 ⁇ mol / min into the processing furnace for 48 seconds is performed.
- TMG having a flow rate of 10 ⁇ mol / min
- TMA having a flow rate of 1.6 ⁇ mol / min
- tetraethylsilane having a flow rate of 0.002 ⁇ mol / min
- ammonia having a flow rate of 300,000 ⁇ mol / min
- the light emitting layer 5 having a 15-cycle multiple quantum well structure with a well layer made of GaInN having a thickness of 2 nm and a barrier layer made of n-type AlGaN having a thickness of 7 nm is obtained as an n-type. It is formed on the surface of nitride semiconductor layer 4.
- a p-type semiconductor layer 6 composed of Al m Ga 1-m N (0 ⁇ m ⁇ 1) is formed on the light emitting layer 5.
- the furnace pressure of the MOCVD apparatus is maintained at 100 kPa, and the furnace temperature is raised to 1025 ° C. while nitrogen gas having a flow rate of 15 slm and hydrogen gas having a flow rate of 25 slm are supplied as carrier gases in the processing furnace.
- nitrogen gas having a flow rate of 15 slm and hydrogen gas having a flow rate of 25 slm are supplied as carrier gases in the processing furnace.
- TMG with a flow rate of 35 ⁇ mol / min
- TMA with a flow rate of 20 ⁇ mol / min
- ammonia with a flow rate of 250,000 ⁇ mol / min
- biscyclopentadiene with a flow rate of 0.1 ⁇ mol / min for doping p-type impurities.
- Enil is fed into the processing furnace for 60 seconds.
- a hole supply layer having a composition of Al 0.3 Ga 0.7 N having a thickness of 20 nm is formed on the surface of the light emitting layer 5.
- a hole supply layer having a composition of Al 0.13 Ga 0.87 N having a thickness of 120 nm is formed on the surface of the light emitting layer 5.
- the content C concentration in the p-type nitride semiconductor layer 6 is as high as about 1 ⁇ 10 19 / cm 3, for example, the content C concentration in the n-type nitride semiconductor layer 4
- the effect of attenuating deep light emission was obtained by setting the value to 1 ⁇ 10 17 / cm 3 or less.
- magnesium (Mg), beryllium (Be), zinc (Zn), carbon (C), or the like can be used as the p-type impurity.
- n-electrode is formed on the upper surface of the exposed n-type nitride semiconductor layer 4, and a p-electrode is formed on the upper surface of the high-concentration p-type GaN layer.
- each element is an ultraviolet light emitting element having a main emission wavelength of 370 nm band.
- Example 1 Created with a V / III ratio of 4000.
- the content C concentration of the n-type nitride semiconductor layer 4 is 5 ⁇ 10 16 / cm 3.
- Example 2 Created with a V / III ratio of 2000.
- the content C concentration of the n-type nitride semiconductor layer 4 is 1 ⁇ 10 17 / cm 3.
- Comparative Example 1 Created with a V / III ratio of 1000.
- the content C concentration of the n-type nitride semiconductor layer 4 is 5 ⁇ 10 17 / cm 3.
- the V / III ratio of the source gas at the time of forming the p-type nitride semiconductor layer 6 is 6000, and the content C concentration of the p-type nitride semiconductor layer 6 is 1 ⁇ 10 17 / cm 3 . there were.
- FIG. 3 is a graph showing the spectral distribution of light obtained when the same voltage is applied to the three elements of Example 1, Example 2, and Comparative Example 1.
- the horizontal axis is the emission wavelength, and the vertical axis is the light intensity.
- FIG. 4 is a photograph showing the light emission state of each element.
- the intensity ratio (deep intensity ratio) of the emission wavelength (deep emission) in the 550 nm-600 nm band including the yellow visible light wavelength band to the emission intensity in the 370 nm band is About 0.3% and over 0.1%.
- the deep intensity ratio of Example 1 is about 0.03%, and the deep intensity ratio of Example 2 is about 0.1%.
- Example 1 and Example 2 the deep intensity ratio is suppressed to 0.1% or less, and even in the photograph of FIG. You can see that Comparing Comparative Example 1, Example 1 and Example 2, it can be seen that the effect of reducing the deep intensity ratio is obtained as the content C concentration of the n-type nitride semiconductor layer 4 is reduced.
- Example 2 the V / III ratio of the source gas at the time of forming the p-type nitride semiconductor layer 6 in a state where the concentration of C contained in the n-type nitride semiconductor layer 4 is 1 ⁇ 10 17 / cm 3. , And the same measurement was performed by increasing the content C concentration of the p-type nitride semiconductor layer 6 to 1 ⁇ 10 19 / cm 3 , but no significant difference from Example 2 was obtained. This also shows that the concentration of C contained in the n-type nitride semiconductor layer 4 affects the deep emission.
- Mg is doped as an impurity of the p-type nitride semiconductor layer 6, it is considered that the light emission derived from the level at C is suppressed by the level created by Mg. For this reason, it is considered that the deep light emission is not affected if the impurity concentration of C contained in the p-type nitride semiconductor layer 6 is at least equal to or less than the Mg doping amount. Since the Mg doping concentration is about 1 to 2 ⁇ 10 19 / cm 3 , if the contained C concentration is about 1 ⁇ 10 19 / cm 3 , deep light emission is not affected. However, as described above, when the n-type nitride semiconductor layer 4 contains the same concentration of contained C, high deep light emission occurs.
- the light emitting layer 5 is also comprised by the n polarity nitride semiconductor, the one where content C concentration is low is preferable.
- the absolute amount of C contained is much smaller than that of the n-type nitride semiconductor layer 4. Therefore, actually, it does not greatly contribute to deep light emission as much as the C concentration of the n-type nitride semiconductor layer 4.
- the LED element 1 shown in FIG. 2 has the support substrate 2 and the undoped layer 3, but may have a configuration (see FIG. 5) in which these are peeled off. In this case, the same effect as described above with reference to FIGS. 3 and 4 was obtained.
- Nitride semiconductor light emitting device 2 Support substrate 3: Undoped layer 4: N-type nitride semiconductor layer 5: Light emitting layer 6: P-type nitride semiconductor layer 51, 52, 53, 54, 55: LED device
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Abstract
Description
本発明の窒化物半導体発光素子1の構造につき、図2を参照して説明する。図2は窒化物半導体発光素子1の概略断面図である。なお、以下では、「LED素子1」と略記する。
支持基板2は、サファイア基板で構成される。なお、サファイアの他、Si、SiC、AlN、AlGaN、GaN、YAGなどで構成しても構わない。
アンドープ層3は、GaNにて形成される。より具体的には、GaNよりなる低温バッファ層と、その上層にGaNよりなる下地層によって形成される。
n型窒化物半導体層4は、不純物として含有されるCの濃度が1×1017/cm3以下となるように形成されたAlnGa1-nN(0<n≦1)によって構成される。この含有C濃度の低下方法については後述される。
発光層5は、例えばGaInNからなる井戸層とAlGaNからなる障壁層が繰り返されてなる多重量子井戸構造を有する半導体層(AlGaInN発光層)で形成される。これらの層はアンドープでもp型又はn型にドープされていても構わない。
p型窒化物半導体層6は、AlmGa1-mN(0<m≦1)によって構成される。なお、p型窒化物半導体層6は、n型窒化物半導体層4とは異なり、不純物として含有されるCの濃度が1×1017/cm3を上回っていても構わない。この点についても後述される。
次に、図2に示したLED素子1の製造プロセスにつき説明する。なお、この製造プロセスはあくまで一例であり、ガスの流量、炉内温度、炉内圧力等は適宜調整して構わない。
支持基板2としてのサファイア基板を準備し、c面サファイア基板のクリーニングを行う。このクリーニングは、より具体的には、例えばMOCVD(Metal Organic Chemical Vapor Deposition:有機金属化学気相蒸着)装置の処理炉内にc面サファイア基板を配置し、処理炉内に流量が10slmの水素ガスを流しながら、炉内温度を例えば1150℃に昇温することにより行われる。
次に、c面サファイア基板の表面に、GaNよりなる低温バッファ層を形成し、更にその上層にGaNよりなる下地層を形成する。これら低温バッファ層及び下地層がアンドープ層3に対応する。
次に、アンドープ層3の上層にAlnGa1-nN(0<n≦1)の組成からなるn型窒化物半導体層4を形成する。
次に、n型窒化物半導体層4の上層にAlGaInNで構成される多重量子井戸構造を有する発光層5を形成する。
次に、発光層5の上層に、AlmGa1-mN(0≦m<1)で構成されるp型半導体層6を形成する。
p型窒化物半導体層6の形成後、TMAの供給を停止すると共に、ビスシクロペンタジエニルの流量を0.2μmol/minに変更して原料ガスを20秒間供給する。これにより、厚みが5nmのp型GaNよりなる高濃度p型GaN層が形成される。
以下、実施例を参照して説明する。
・実施例2: V/III比を2000として作成。n型窒化物半導体層4の含有C濃度は1×1017/cm3
・比較例1: V/III比を1000として作成。n型窒化物半導体層4の含有C濃度は5×1017/cm3
図2に示すLED素子1は、支持基板2及びアンドープ層3を有するものとしたが、これらを剥離した構成(図5参照)としても構わない。この場合においても、図3及び図4を参照して上述したものと同様の効果が得られた。
2 : 支持基板
3 : アンドープ層
4 : n型窒化物半導体層
5 : 発光層
6 : p型窒化物半導体層
51,52,53,54,55 : LED素子
Claims (3)
- n型窒化物半導体層とp型窒化物半導体層の間に発光層を有する窒化物半導体発光素子であって、
前記n型窒化物半導体層は、AlnGa1-nN(0<n≦1)を含み、含有されるC濃度が1×1017/cm3以下であることを特徴とする窒化物半導体発光素子。 - 主たる発光波長が375nm以下の紫外光発光素子であることを特徴とする請求項1に記載の窒化物半導体発光素子。
- 黄色の可視光波長の発光強度が、前記主たる発光波長の発光強度に対して強度比が0.1%以下であることを特徴とする請求項2に記載の窒化物半導体発光素子。
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JP2005101536A (ja) | 2003-08-28 | 2005-04-14 | Nichia Chem Ind Ltd | 窒化物半導体レーザ素子 |
WO2007013257A1 (ja) | 2005-07-29 | 2007-02-01 | Matsushita Electric Industrial Co., Ltd. | 窒化物系半導体素子 |
US20100163931A1 (en) | 2006-03-20 | 2010-07-01 | Kanagawa Academy Of Science And Technology | Group iii-v nitride layer and method for producing the same |
JP4599442B2 (ja) * | 2008-08-27 | 2010-12-15 | 株式会社東芝 | 半導体発光素子の製造方法 |
JP5549338B2 (ja) * | 2010-04-09 | 2014-07-16 | ウシオ電機株式会社 | 紫外光放射用窒素化合物半導体ledおよびその製造方法 |
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JPH09186403A (ja) * | 1995-12-27 | 1997-07-15 | Sharp Corp | 半導体発光素子及びその製造方法 |
JPH11195808A (ja) * | 1997-12-26 | 1999-07-21 | Fuji Xerox Co Ltd | 光半導体素子およびその製造方法 |
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JP2007201099A (ja) * | 2006-01-25 | 2007-08-09 | Sumitomo Electric Ind Ltd | 窒化物半導体発光素子を作製する方法 |
JP2008266113A (ja) * | 2006-08-28 | 2008-11-06 | Kanagawa Acad Of Sci & Technol | Iii−v族窒化物層およびその製造方法 |
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